CSLB C-27 Landscaping ContractorSite Preparation and DrainageMedium
A C-27 contractor is preparing a site for a new planting area on a recently graded hillside. To provide immediate, temporary erosion control on the bare soil until permanent vegetation can establish, which of the following methods is most appropriate?
- APlanting mature shrubs and trees
- BInstalling a permanent retaining wall
- CApplying straw wattles along the contour
- DHydroseeding with a permanent seed mix
Show answer & explanationAnswer & explanation
Correct answer: C. Applying straw wattles along the contour
Straw wattles (or fiber rolls) are effective temporary erosion control devices used on slopes. They are placed along the contour to slow runoff, trap sediment, and allow water to infiltrate, protecting the soil until permanent stabilization methods (like vegetation) are established.
Why the other options are wrong
- A. Planting mature shrubs and trees is a long-term, permanent erosion control method, but it does not offer immediate protection for bare soil.
- B. Installing a permanent retaining wall is a structural, long-term solution for slope stabilization, not a temporary erosion control method.
- D. Hydroseeding with a permanent seed mix is a permanent stabilization method, not an immediate temporary one before establishment; it takes time to germinate and grow.
Temporary Slope Erosion Control
Temporary erosion control methods like straw wattles are used on bare slopes to slow runoff and trap sediment until permanent vegetation or structures are established.
- Protects soil from rain and wind erosion.
- Slows water velocity, promoting infiltration.
- Prevents sediment from leaving the site.
Memory trick: Wattles for temporary, seeds for eternity.